1968 Camaro LS Engine - Reality Check

We Build A Wallet-Friendly Mill For Project Track Rat And Hit The Dyno.

•When does "just a little bit more" become too much of a good thing? The answer is that it occurs a lot sooner than most gearheads think. We're not sure when it happened, but at some point an engine didn't start becoming impressive until it was churning out 700, 800, or even 900 hp. In the never-ending quest to keep up with the Joneses, guys started one-upping each other in terms of both displacement and power. Blowers begat turbos, which then gave way to twin turbos. It became a race to see who could be the next king of the hill. Only one problem: said hill is made out of cash. Ironically, in the world of street machines, and Pro Touring cars, a 700hp twin-turbo engine is nearly useless. Have you ever had a pair of turbos go into boost during the apex of a curve? Let's just say it's an easy way to morph a 90-degree turn into a 360-degree spinfest. Straightline performance is tough as well since even massive, 335 tires end up being spun into molten slag by an overabundance of power.

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And while we dig a car with bodacious amounts of power as much as the next guy, the reality is that you don't really need that much power to have fun. Besides, a more moderately powered engine means you'll have more cash to spend on other areas of your car.

From the beginning we knew our '68 Track Rat project car was going to be LSpowered, but we wanted to try something a bit different. Instead of building the biggest, baddest LS engine possible, the idea became to scale things down a bit and see what we could do with less displacement. We've always felt that the 5.3L version of The General's LS series had been somewhat overlooked. The downside was the iron block added unwanted weight to the front of car and this certainly didn't help handling. One afternoon we were at Turn Key Engine Supply and noticed that they had a few pallets of 5.3L blocks on hand, but what really got our cranial gears turning was that these were aluminum versions. The idea gelled in our heads to build a 5.3L all-aluminum engine that would use mostly GM parts to keep the costs down. To get the power up a bit we would drop in a few aftermarket widgets, but overall our goal would be to get good power at a reasonable cost. Also, while our mill featured an aluminum block, all of the tech will translate to someone wanting to tackle an even more frugal iron block version.

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Power Parts Costs
•When it came time to figure out the cost of Track Rat's mill we stumbled over the quandary of what to include. Some items like pretty ARP accessory fasteners didn't affect the power at all. The head studs were a choice we made to facilitate future head swap stories and could easily be replaced with GM head bolts at our power levels. With that in mind, we decided to just go with the core parts needed to hit these dyno numbers and stay in one piece. Turn Key also offers a selection of oil pans and accessories to make dropping an LS engine into your Camaro a snap. In particular, their five-wire harness and MEFI 4 computer makes doing a swap nearly painless. If you don't mind the weight penalty you could swap out an iron block. We also ran the same short-block with a smaller cam, GM rockers, and factory heads. Power dropped to 408/416, but the combo cost around $1,500 less. Whatever your budget or horsepower goals are, Turn Key has just the engine to motivate your Camaro.

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1968 Camaro LS Engine - Reality Check

With an electric water pump in place to make plumbing on the dyno a bit easier, we were finally ready to make our first pulls on the 5.3L Track Rat mill. The dyno is a Superflow 901 and we ran 91-octane pump gas with the same Dynatech headers we will be running in the Camaro.

The key player in our build is this Gen III 5.3L aluminum crossbolted block, also referred to as an LM4 (PN 12566910 or 12571048). Originally designed for an '04 Chevy SSR, Trailblazer EXT, GMC Envoy XL, and Buick Rainiers, it shares almost all the attributes of its larger displacement cousins. Theoretically, due to the liner thickness, we could have bored it out to a 5.7L, but if we wanted that we would have just picked up an LS1. Besides, our Camaro originally came with a 327 so this displacement had a bit of nostalgia. The only machining done was a light "clean up" hone to the cylinders.

The cast 5.3L cranks have the same stroke as their 5.7L cousins. They are inexpensive, plentiful, and perfect for a build like this. Ours came with the proper 24x reluctor wheel.

To get a little bit more compression, we opted to run the flat top 4.8L pistons rather than the dished 5.3L slugs. The GM stuff uses a pressed fit rather than a floating pin, so Turn Key heated up the rods and mated the pistons to the 5.3L rods. Also, unlike some of the earlier 5.3L versions, these GM 4.8L pistons have a moly coating on the skirts as an added "freebie" bonus.

Using a 3.796-inch sleeve, we slid the assembled pistons and rods into their holes. We whipped out our trusty compression ratio calculator, punched in the data and came up with an effective ratio of about 11.5:1. The key to hitting this number was moving from the 5.3L to the 4.8L flat top pistons. On 91 octane, with proper tuning by Turn Key, there was zero detonation.

We went with a factory GM oil pump, but we upgraded to a stronger Progear timing chain (PN PG4158). Since this engine uses a 24x reluctor wheel, just the chain and lower sprocket was used along with a GM upper sprocket.

In regards to the camshaft selection, we wanted something that would up the output, but not kill the street manners of the 5.3L engine. We settled on this Trick Flow Track Max bumpstick (PN TFS-30602002, $349.95). With a duration of 220/224 (at 0.050-inch) and 0.575-inch lift, this 112 LSA hydraulic roller cam should give us the best of both worlds.

The factory bolts in the rods were rated up to 450 hp, but because that was our target output, we decided to upgrade to a set of ARP fasteners (PN 134-6006, $77.95) and torqued them to spec.

To clear our Chassiworks subframe, we needed to run an F-Body-style LS oil pan. Luckily we had one left over from another project . To help control oil better during hard cornering, we ditched the factory baffle and dropped in this trap-door style unit from Improved Racing (PN FB-TD-Baffl, $199).

Before installing the oil pan we put the F-body pickup and windage tray in place and dabbed a little RTV sealant at the four corners of the oil pan to ensure a leak-free seal.

To dress up the engine a bit we picked up ARP's oil pan bolt kit (PN 434-6901, $55.95). There's a hole on the side of the pan for an oil level sender that's used in factory applications. Turn Key makes this sweet plug, but they also make one with a 1/8-inch pipe hole. It's ideal for an oil temperature sender.

For our purposes there's nothing wrong with the very reliable GM hydraulic rollers. The GM lifter guides keep the lifters in the proper perpendicular orientation and make cam swaps a snap.

Trick Flow saw the potential of these 4.8L and 5.3L engines sometime ago and decided to churn out a set of heads perfect for their smaller displacements. Their GenX street CNC-ported heads (PN TFS-30500001-C00, $1,995.95) feature refined combustion chambers to work with the smaller bore diameters. They also modified the chambers to unshroud the valves and increase airflow and swirl. They feature fully CNC-machined and bowl-blended chambers along with CNC-ported runners for max airflow. Components include lightweight, stainless steel 2.000-inch intake and 1.575-inch exhaust valves, high lift springs, chromoly retainers, ductile iron valve seats, and special Trick-Alloy powdered metal valve guides. Out of the box they have 58cc combustion chambers, 205cc intake runner volume, and 80cc exhaust runner volume.

Nothing fancy here, just good old reliable GM head gaskets from Summit (PN 12498544, $29.95 a pair). The Trick Flow heads were set in place, then secured with a set of ARP head studs (PN 234-4110, $249.95). We like the ARP units since they are reusable in addition to being stronger. You could save a few bucks by going with the factory bolts, but remember to always get new ones since they are torque-to-yield. Also, keep in mind that the holes are blind so it's crucial to make sure they are clean and void of any liquid or debris.

Turned out that the perfect length for the push rods ended up being 7.500-inches. These hardened chromoly Trick Flow sticks (PN TFS-21407500, $86.95) will be able to stand up to the punishment we plan on putting our '68 through once it finally hits the road.

One area where we did splurge a bit was our rockers. While we could have run the very capable GM rockers, we've really been itching to try these pedestal-mount roller rockers from Harland Sharp (PN SLS17, $369.95). While their 1.7 ratio was a perfect match to our Trick Flow heads, they are also offered in a 1.8 ratio. The 1.8s would have yielded us a little more power, but we would have been pushing the capabilities of our springs. In the end, we decided longevity was more important than a slightly higher dyno number. Another advantage to these slick orange beauties is that they are designed to clear the stock height valve covers.

More ARP stainless fasteners were used to secure the 5.3L specific valley cover in place. The holes in the center are for the factory knock sensors.

This Fluidampr (PN 620131) dampener is actually part of the Concept One drive system kit we will eventually be installing on the engine. Rather than running a less-expensive stocker, we decided to save some effort and just put it on now. It's held in place by a reusable ARP bolt (PN 234-2503, $27.95).

When it comes to intakes there are many options to go with, from dirt cheap truck intakes to aftermarket versions from companies like FAST. A great "bang-for-the-buck" option is this LS2 intake. They can be bought brand new at a reasonable price and are prolific on the used market. We teamed it up with one of Turn Key's 90mm throttle bodies. One clever thing that Turn Key does is to drill a hole and mount the inlet air temp (IAT) sender in the intake just behind the throttle body.

To keep things simple we decided to run 36-pound LS2 injectors and fuel rail with the LS2 intake. To make plumbing easier, Turn Key modifies the fuel rail with an -AN fitting instead of the factory connector.

To get an idea of how our final engine will look, we went ahead and bolted on the Tough Stuff water pump, also a part of the Concept One pulley system, and the Dynatech MuscleMAXX 1 7/8-inch long tube headers PN (115-911400). These are the tubes we will be running once this mill is sitting between Track Rat's fenders. To further improve the aesthetics, we added a set of GM Performance Parts cast valve covers (PN 25534399, $119.95 ea). They go a long way to making the somewhat homely LS engine look good.

Some people prefer to break in engines on traditional oil, but with hydraulic roller LS engines, there's really no need, after all, the factory often starts them off on synthetic. In this case we dropped in six quarts of Torco SR-1 5W30 oil. The Torco oil is rich in the additives that have been ripped out of many other oils.

Once Kory Enger worked his tuning magic on the 5.3L, we were rewarded with a best pull of 491 hp at 6,100 rpm and 445 lb-ft of twist at 5,000 rpm. These numbers were correct to our usual SAP standards, and on dyno day the correction factor was 1.046.

Even better than the peak numbers was how flat the torque curve was for an engine of such modest displacement-385 lb-ft of torque down at 2,900 rpm. Certainly more than enough grunt to motivate our '68 project car down the tarmac.